Fayetteville, North Carolina: Democratic presidential hopeful Barack Obama belittled Republican John McCain on Wednesday for misidentifying Iraqi extremists, saying he fails to understand the war has emboldened US enemies.

On the fifth anniversary of the US-led invasion of Iraq, Democrats Obama and New York Senator Hillary Clinton both pledged to withdraw US troops speedily from Iraq if either of them is elected in November, while McCain held firm to his position that a troop build-up was paying off and should be maintained.

McCain, 71, who touts his national security experience as a reason why he should be elected, gave Democrats a line of attack to use against him on Tuesday.

On a Middle East and Europe swing, he got tangled up in stating which extremist group in Iraq that Iran is accused of supporting.

Corrected by colleague

At a news conference in Amman, McCain said Iran supported the Sunni group Al Qaida in Iraq, until he was corrected by a colleague. US officials believe Iran has been backing Shiite extremists in Iraq, not a Sunni group like Al Qaida.

It was the first stumble of note that McCain has made since clinching the Republican presidential nomination early this month.

"Just yesterday, we heard Senator McCain confuse Sunni and Shiite, Iran and Al Qaida," Obama said.

"Maybe that is why he voted to go to war with a country that had no Al Qaida ties. Maybe that is why he completely fails to understand that the war in Iraq has done more to embolden America's enemies than any strategic choice that we have made in decades," he said.